In order to alleviate shift shock when performing a power-on downshift (kick-down) in a conventional hydraulic control apparatus of an automatic transmission which controls a shifting operation by changing over a plurality of friction engaging elements such as clutches and brakes, control is executed to reduce the shock by mechanically controlling hydraulic pressure using timing valves.
One example of a hydraulic control apparatus using timing valves of this kind is disclosed in the specification of Japanese Patent Application Laid-Open (KOKAI) No. 63-214550 (1988). This disclosed apparatus has a downshift timing valve connected to the release side of a brake element actuator, and is adapted to alleviate shift shock at the time of a downshift by controlling the operation of the timing valve.